Various medical devices used in a living body such as an artificial blood vessel, artificial organs or the like can require affinity for blood, body fluids, or a living tissue. Among them, antithrombogenicity preventing blood from clotting is important in a medical device coming into contact with blood.
In general, antithrombogenicity is provided to a medical device by performing a method for coating a base material for forming a medical device with an antithrombotic material, or a method for fixing an antithrombotic material on a surface of a base material.
For example, a method has been known in which the absorption of a biogenic component to the surface of the base material is physicochemically inhibited and the formation of the thrombus on the surface of the base material is inhibited, by graft-polymerizing a water-soluble polymer material on the surface of the base material. However, there have been problems with the method that the blood plasma protein enters the surface-grafted layer over time, coagulation due to a blood plasma component or a platelet activated on the surface of the base material influences a living body, and the like. Furthermore, there are also problems that the production process of the method is complicated and there is a great restriction in view of the type of the base material to be grafted.
In addition, another method also has been known in which the antithrombogenicity is provided to the surface of the base material by fixing a material such as heparin having anticoagulant activity on the surface of the base material, or by sustainably releasing the aforementioned material from the surface of the base material. However, there are problems with the biological substance such as the heparin that the anticoagulant activity of the biological substance deteriorates by sterilization treatment after fixing the biological substance on the surface of the base material, the biological substance is decomposed by enzyme in a living body so that the activity cannot be maintained for a long period of time, and it is impossible to apply to compounds other than the heparin having the anticoagulant activity in view of safety issues.
In contrast to the above, a sulfonate group-containing polymer such as a poly-2-acrylamide-2-methyl propane sulfonic acid (PAMPS) has been known as the antithrombotic material which is excellent in the anticoagulant activity and sterilization resistance and which can improve safety and durability.
As a method for fixing the PAMPS on the surface of the base material, for example, Patent Literature 1 discloses a method for fixing the PAMPS on the surface of the base material such that a 2-acrylamide-2-methylpropanesulfonic acid (AMPS)-acrylic acid copolymer is coated after coating a polymer (reactive compound), which has an epoxy group or an isocyanate group reacting with a carboxyl group, on the surface of the base material, and the epoxy group or the isocyanate group is reacted with the carboxyl group by heating or the like to form a chemical bond.
Meanwhile, the medical device can require having a lubricating surface for the purpose of reducing tissue damage or improving operability. As an example of the surface lubrication, Patent Literature 2 discloses a method for forming a surface lubrication layer containing a reaction product between a hydrophilic polymer compound and a cross-linking agent including a hydrazide compound. In addition, according to the method, it is possible to provide the lubricity and the antithrombogenicity to the surface of the base material by performing the surface lubrication treatment in coexistence with a water-soluble physiologically active substance such as the heparin.    Patent Literature 1: JP-A-09-131396    Patent Literature 2: U.S. Pat. No. 6,540,698
However, since the method disclosed in Patent Literature 1 requires heating for the reaction between the epoxy group or the isocyanate group and the carboxyl group to fix the antithrombotic material on the surface of the base material, there is a problem that the type or the form of the base material is limited. Furthermore, since the method utilizes the reaction between a highly reactive proton-accepting functional group such as the epoxy group and a proton-donating functional group, the solvent is limited to a non-proton-donating organic solvent, coating procedure is complicated, and the production process is complicated because it is necessary to strictly control moisture of the coating solution or the working area. In addition, there is a problem that the safety and the durability are insufficient in the method of Patent Literature 2 because the method utilizes the heparin or the like to give the antithrombogenicity.